In children, poor posture is caused by many factors including, malnutrition and altered habitual positions. Poor postures may develop into fixed spinal deformities, and could negatively affect the physical and psychological well-being of children. In this study, we examined the screened prevalence of spinal deformities and characterized the type and distribution of deformities in 3 606 (mean age 19.3±2.1) Rwandan secondary school children. We screened the postures of children using the Modified Posture Screen test and the Adams Forward Bend test. Relationships between categorical variables and spinal disorders were investigated with the Chi-square test. The screened prevalence of spinal deformities was 53.3% (95% CI 51.7; 55). Scoliosis was most the common deformity at 39% (95% CI 38%; 41%). Female gender (p = .029) and low body mass index (p = .002) were significantly associated with the presence of spinal deformities. Our finding points to the need for a follow up evaluation during which positively screened children undergo clinical examination and treatment as needed. At the population level, educators and nurses should be trained to screen for spinal deformities, to ensure that all schoolchildren in Rwanda have access to proper screening and necessary intervention.